US8282525B2 - Arrangement for control of a continuosly variable transmission - Google Patents

Arrangement for control of a continuosly variable transmission Download PDF

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Publication number
US8282525B2
US8282525B2 US12/308,199 US30819907A US8282525B2 US 8282525 B2 US8282525 B2 US 8282525B2 US 30819907 A US30819907 A US 30819907A US 8282525 B2 US8282525 B2 US 8282525B2
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Prior art keywords
variator
arrangement
torque transfer
transfer part
ratio
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Expired - Fee Related, expires
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US12/308,199
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US20090318259A1 (en
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Robert Andrew Oliver
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Torotrak Development Ltd
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Torotrak Development Ltd
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Assigned to TOROTRAK (DEVELOPMENT) LIMITED reassignment TOROTRAK (DEVELOPMENT) LIMITED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: OLIVER, ROBERT ANDREW
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/66—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/66—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings
    • F16H61/664—Friction gearings
    • F16H61/6648—Friction gearings controlling of shifting being influenced by a signal derived from the engine and the main coupling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H15/00—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members
    • F16H15/02—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members without members having orbital motion
    • F16H15/04—Gearings providing a continuous range of gear ratios
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/66—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings
    • F16H61/664—Friction gearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H63/00—Control outputs from the control unit to change-speed- or reversing-gearings for conveying rotary motion or to other devices than the final output mechanism
    • F16H63/02—Final output mechanisms therefor; Actuating means for the final output mechanisms
    • F16H63/04—Final output mechanisms therefor; Actuating means for the final output mechanisms a single final output mechanism being moved by a single final actuating mechanism
    • F16H63/06—Final output mechanisms therefor; Actuating means for the final output mechanisms a single final output mechanism being moved by a single final actuating mechanism the final output mechanism having an indefinite number of positions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H63/00—Control outputs from the control unit to change-speed- or reversing-gearings for conveying rotary motion or to other devices than the final output mechanism
    • F16H63/02—Final output mechanisms therefor; Actuating means for the final output mechanisms
    • F16H63/04—Final output mechanisms therefor; Actuating means for the final output mechanisms a single final output mechanism being moved by a single final actuating mechanism
    • F16H63/06—Final output mechanisms therefor; Actuating means for the final output mechanisms a single final output mechanism being moved by a single final actuating mechanism the final output mechanism having an indefinite number of positions
    • F16H63/065—Final output mechanisms therefor; Actuating means for the final output mechanisms a single final output mechanism being moved by a single final actuating mechanism the final output mechanism having an indefinite number of positions hydraulic actuating means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/24—Providing feel, e.g. to enable selection

Definitions

  • the present invention is concerned with control of continuously, variable transmissions.
  • a conventional motor vehicle transmission with a manual, stepped ratio gearbox typically has a user operable clutch between the engine and the gearbox serving to couple/decouple them.
  • the vehicle When the vehicle is launched—that is, when it moves away from rest—there is an inevitable initial mismatch of speeds between the transmission input and the engine output, and by allowing the clutch to slip at this stage the driver causes torque to be applied to the transmission to accelerate the vehicle, without applying an unsustainable load to the engine that would cause it to stall.
  • the initial mismatch of speeds is accommodated by a torque converter.
  • the clutch and torque converter are examples of what will be referred to herein as “launch devices”.
  • CVTs continuously variable transmissions
  • geared neutral a condition in which the transmission output is stationary while the engine is running.
  • Launch can be achieved simply by moving the CVT ratio away from geared neutral, and it is not necessary to decouple the transmission from the engine to bring the vehicle to a halt.
  • engine is used herein for the sake of brevity to refer to any form of rotary driver, and must be understood to encompass not only internal combustion engines but also electric motors, external combustion engines etc.
  • variable will be used herein to refer to a device that has a rotary input and a rotary output and that transfers drive from one to the other at drive ratio that can be continuously varied. Such a device is to be found in any CVT.
  • variators have some movable torque transfer part which is involved in the transfer of drive and whose position corresponds to the variator ratio.
  • rollers serve as the movable torque transfer parts. They transmit drive from one toroidally recessed race to another, and their motion involves a change in roller inclination which is associated with a change in variator drive ratio.
  • a force is applied to the movable torque transfer part to influence its position, and so to influence variator drive ratio.
  • this force could be provided through some direct linkage to a user operable control such as a lever or foot pedal.
  • the force required which is related to the torques suffered by the variator—proves to be too large to be comfortably provided by the user.
  • Achieving geared neutral with such an arrangement could also be problematic, since any minor deviation of the position of the torque transfer part from the position required for geared neutral would cause the transmission to adopt a very low drive ratio, potentially resulting in a large “creep torque”, albeit at low wheel speed.
  • an arrangement for controlling a variator comprising a user operable ratio control part, a device for operatively coupling the ratio control part to a movable torque transfer part of the variator to enable the user to exercise control over the variator ratio, and a torque release device operable by the user to decouple the ratio control part from the movable torque transfer part.
  • the ratio control part may for example be a foot pedal or lever operable by the user.
  • the operative coupling of the ratio control part to the torque transfer part is preferably such that the position of the torque transfer part is determined by the position of the ratio control part.
  • an arrangement for controlling a variator comprising a user operable ratio control part, a device for operatively coupling the ratio control part to a movable torque transfer part of the variator to enable the user to exercise control over the variator ratio, and a device for applying to the ratio control part a force which varies in sympathy with force experienced by the movable torque transfer part.
  • FIG. 1 is a highly simplified and schematic representation of a variator suitable for use in implementing the present invention
  • FIG. 2 is a schematic representation of a CVT suitable for use in implementing the present invention.
  • FIG. 3 is a schematic representation of a control arrangement embodying the present invention.
  • FIG. 1 represents a variator of the well known toroidal race, rolling traction type.
  • the present invention has been developed in connection with a CVT using this type of variator, which is particularly well suited to the purpose, but in principle variators of other types could be used.
  • the variator 10 comprises co-axially mounted input and output races 12 , 14 , adjacent faces 6 , 8 of which are semi-toroidally recessed and together define a generally toroidal cavity 16 containing a movable torque transfer part in the form of a roller 18 .
  • a practical variator typically has two or three such rollers spaced about the cavity 16 at circumferential intervals.
  • Each roller 18 runs upon the faces 6 , 8 of the respective races 12 , 14 and so serves to transmit drive from one to the other.
  • the roller 18 is able to move back and forth along a circumferential direction about the common axis 20 of the races 12 , 14 . It is also able to precess.
  • the roller's axis is able to turn, changing the inclination of the roller axis to the disc axis.
  • these motions are provided for by rotatably mounting the roller 18 in a carrier 22 coupled by a stem 24 to a piston 26 of an actuator 28 .
  • a line 19 from the centre of the piston 26 to the centre of the roller 18 constitutes a precession axis about which the whole assembly can turn. Precession of the roller results in changes of the radii of the paths traced upon the races 12 , 14 by the roller, and hence in a change of variator drive ratio.
  • the precession axis 19 does not lie precisely in a plane perpendicular to the common axis 20 , but is instead inclined to this plane.
  • the angle of inclination is labelled CA in the drawing, and is known as the “castor angle”.
  • CA The angle of inclination
  • the roller moves back and forth it follows a circular path centred upon the common axis 20 .
  • the action of the races 12 , 14 upon the roller creates a steering moment which tends to maintain it at such an inclination that the roller axis intersects the common axis 20 .
  • This intersection of the axes can be maintained, despite movement of the roller back and forth along its circular path, by virtue of the castor angle.
  • the roller As the roller moves along its path, it is also steered by the action of the races, causing it to precess such as to maintain the intersection of the axes. The result is that the position of the roller along its path corresponds to a certain roller inclination and hence to a certain variator drive ratio.
  • the actuator 28 receives opposed hydraulic fluid pressures through lines 30 , 32 .
  • the force thus created by the actuator 28 urges the roller along its circular path about the common axis 20 , and at equilibrium it is balanced by forces exerted upon the roller by the races 12 , 14 .
  • the force exerted by the races is proportional to the sum of the torques externally applied to the variator races. This sum—the variator input torque plus the variator output torque—is the net torque that must be reacted to the variator's mountings, and is referred to as the reaction torque.
  • an engine is represented by a box ENG, the variator by a circle V and an epicyclic shunt gear by a box E.
  • the variator input is coupled to the engine through gearing R 1 , R 2 . Its output is coupled to a first input shaft S 1 of the epicyclic shunt E.
  • a second input shaft S 2 of the epicyclic shunt E is coupled through fixed ratio gearing R 1 , R 3 to the engine.
  • An output shaft S 3 of the epicyclic shunt E is coupled through gearing R 4 to the point of power usage, in this case wheels W of a motor vehicle.
  • the operation and construction of epicyclic gear is very well known.
  • the speed of the output shaft S 3 can be expressed as a function of the speeds of the input shafts S 1 , S 2 . At some variator drive ratio, the speeds of S 1 and S 2 cancel each other out and the output speed at S 3 is zero whatever the speed of the engine. This is the “geared neutral” condition referred to above. Variator drive ratios to one side of geared neutral produce S 3 output rotation in one direction and variator drive ratios to the other side of geared neutral produce S 3 output rotation in the opposite direction.
  • a control arrangement embodying the present invention will now be described with reference to FIG. 3 , in which the variator's control actuator and piston are once more labelled 28 and 26 respectively.
  • the arrangement serves to control the hydraulic pressures applied to the actuator which in turn control variator ratio.
  • a user operative ratio control part is seen at 50 in the drawing.
  • the ratio control part is operatively coupled to the variator rollers. The user moves this part to control the ratio adopted by the variator and hence by the transmission as a whole.
  • the variator ratio is a function of the position of the ratio control part.
  • the ratio control part is movable through a continuous range, indicated by arrows in the drawing, from a maximum forward ratio position through a geared neutral position to a maximum reverse ratio position. The range of ratios in forward and reverse will typically be different, making higher outputs speeds available in forward than in reverse.
  • the ratio control part is in this embodiment formed by a hand lever. It could alternatively be a pedal.
  • Pedal mechanisms are known in which the driver, using both the ball and heel of the foot, can rock the pedal to either side of a neutral position. These would be well suited in this context, but an alternative would be to give the driver two pedals—one for forward drive and one for reverse.
  • the device used to operatively couple the ratio control part to the variator rollers is seen in the drawing and is hydro-mechanical. To briefly summarise its main components, it uses a comparator arrangement 52 which receives and compares (a) the position of the ratio control part and (b) the position of the variator rollers, and in response modulates a force to move the rollers toward the position dictated by the user through the ratio control part. This force is provided through a hydraulic pressure control arrangement 54 supplying fluid pressure to the actuator 28 . The device also serves to apply a feedback force, indicative of variator torque, to the ratio control part, to provide the user with information about torque. This is done through a force feedback arrangement 56 .
  • the user is provided with a torque release control 58 which, acting through a torque release device 60 , serves to operatively decouple the ratio control part 50 from the variator and so to zero variator reaction torque, thereby providing functionality which is in some ways similar to that provided by a clutch in a conventional manual transmission.
  • the comparator uses a system of mechanical levers.
  • the lever forming the ratio control part 50 is pivoted about a fixed fulcrum 62 and extends beyond the fulcrum to a pivotal link with a bridging part 64 , which in turn has a first pivotal comparator linkage 65 to a comparator bar 66 .
  • moving the ratio control part 50 moves the comparator bar's first comparator linkage 65 .
  • the piston 26 is in the present embodiment coupled to the comparator bar through a cable linkage 68 and a feedback torque device 70 (the function of the feedback torque device 70 will be described below).
  • the feedback torque device is pivotally coupled to the comparator bar 66 through a second comparator linkage 72 .
  • the position of the second comparator linkage corresponds to the position of the variator roller, and so to the variator ratio.
  • the comparator bar 66 has a reference linkage 74 to a valve control bar 76 leading in turn to a pressure control valve 78 .
  • the effect of the lever arrangement is to set the state of the pressure control valve 78 on the basis of a comparison of variator ratio against the position of the ratio control part 50 .
  • the pressure control valve 78 forms part of the pressure control arrangement 54 . It has a port which receives pressurised fluid through fluid line 80 from a pump 82 .
  • the pump 82 draws from a sump 84 and is provided with a pressure relief valve 86 .
  • the pressure control valve has ports communicating with two supply lines S 1 , S 2 arranged to supply fluid respectively to opposite sides of the variator piston 26 . Pressure in S 1 urges the piston 26 one way. Pressure in S 2 urges it the other way.
  • the pressure control valve 78 is a proportional valve with three states. In one, it applies pressurised fluid from a pump to S 1 . In another it applies the pump fluid to S 2 . In the third, intermediate, state, it isolates S 1 and S 2 from the pump pressure.
  • the first comparator linkage 65 is moved. In this example, let us take it the movement is to the left as viewed.
  • the reference linkage 74 is thus also moved leftward, causing the pressure control valve to adopt its second state, applying pump pressure to S 2 and venting S 1 to the sump. Resultant pressure on piston 26 urges it to the left, as viewed, moving the piston and changing variator ratio.
  • This motion is transmitted through the cable linkage 68 , moving the second comparator linkage to the right.
  • the pressure control valve 78 returns to its third position to maintain the piston pressure and position.
  • the force feedback arrangement 56 applies to the user operative ratio control part a force which corresponds to torque.
  • the force feedback arrangement comprises a double acting arrangement of a piston 88 and cylinder 90 . To opposite sides of the piston are applied pressures taken directly from respective supply lines S 1 , S 2 .
  • the force thereby applied to the ratio control part is thus proportional to the force applied to the variator rollers by the variator piston 26 , although by suitable choice of piston areas it is ensured that the former is smaller than the latter.
  • the force on the variator rollers is proportional to the variator reaction torque so the user experiences a feedback force which is directly related to reaction torque.
  • the torque release control 58 this may for example be a hand lever or foot pedal.
  • the driver is able to set to zero the force applied to the variator rollers.
  • variator reaction torque is likewise set to zero, and the variator is rendered incapable of sustaining an output torque to drive the vehicle wheels.
  • the effect is akin to declutching in a conventional manual transmission, in that it prevents the transmission from applying torque to the vehicle wheels, but is achieved without any physical decoupling of the engine from the wheels. Instead it relies upon operatively decoupling the variator rollers from the ratio control part 50 .
  • the torque release control part 58 acts upon a torque release device 60 formed in this embodiment as a torque release valve leading from one fluid supply line S 1 to the other S 2 .
  • the valve When open, the valve provides a route for equalisation of pressures in the supply lines. With little or no pressure difference across the piston, no significant force is applied to the variator rollers and so no significant reaction torque can be sustained. Closing the torque release valve 60 restores reaction torque.
  • the valve 60 is a proportional valve so that the user can adjust its degree of opening.
  • the torque release control can be used analogously to the type of launch device described above, by first setting the ratio control part 50 to demand forward or reverse drive and then progressively closing the torque release valve 60 to bring the ratio in a controlled manned to the demanded value, causing the vehicle to accelerate away from rest.
  • the torque release control can be used to gently “inch” the vehicle toward a desired position, as when parking. In this case it serves to limit the wheel torque, again in a manner very much akin to the conventional clutch.
  • the torque release control can also be used to release any creep torque, e.g. when the vehicle is parked with the engine running. Note however that the user can also control the transmission without use of this control. For example, he/she can “shuttle” from forward to reverse and vice versa using only the ratio control part 50 .
  • the feedback torque device 70 has yet to be described. It serves to modify variator ratio based upon reaction torque. It comprises a cylinder 91 which is movable by the cable linkage 68 and which contains a piston 92 connected through a bridging part 94 to the second comparator linkage 72 . Within the cylinder 91 are springs on either side of the piston 92 , biasing it toward a certain position. The forces applied to the piston in controlling the pressure control valve 78 are not large, and the springs are stiff enough that little if any movement of the piston 92 in its cylinder is created by these forces. However the piston is also subject, via a shutoff valve 96 , to the S 1 /S 2 pressures.
  • the result is that a sufficient reaction torque—and correspondingly a sufficient difference in the S 1 and S 2 pressures—causes the piston to move against the springs, changing the effective length of the linkage from the cable 68 to the comparator bar 66 .
  • the effect is to modify variator ratio in a manner that reduces reaction torque, giving the system some compliance and protection against excessive torque.
  • the shutoff valve removes this facility, by isolating the feedback torque device from the S 1 /S 2 pressures, when it is not required.
  • Items 98 and 100 in FIG. 3 are hydraulic dampers. Their function is to damp unwanted oscillatory behaviour of the variator by providing some resistance to flow into/out of the piston 28 .
  • Item 102 is a crossover valve used to reverse pressures applied to the variator for overrun conditions.
  • the lever arrangement used to compare roller position and demanded ratio could be replaced by a known type of valve in which the spool and sleeve are movable by the rollers and the ratio control part.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Friction Gearing (AREA)
  • Control Of Transmission Device (AREA)
  • Gear-Shifting Mechanisms (AREA)
  • Transmissions By Endless Flexible Members (AREA)
  • Transmission Devices (AREA)
US12/308,199 2006-06-08 2007-05-11 Arrangement for control of a continuosly variable transmission Expired - Fee Related US8282525B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB0611265.0 2006-06-08
GBGB0611265.0A GB0611265D0 (en) 2006-06-08 2006-06-08 Arrangement for control of a continuously variable transmission
PCT/GB2007/050258 WO2007141564A2 (en) 2006-06-08 2007-05-11 Arrangement for control of a continuously variable transmission

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Publication Number Publication Date
US20090318259A1 US20090318259A1 (en) 2009-12-24
US8282525B2 true US8282525B2 (en) 2012-10-09

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US12/308,199 Expired - Fee Related US8282525B2 (en) 2006-06-08 2007-05-11 Arrangement for control of a continuosly variable transmission

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US (1) US8282525B2 (de)
EP (1) EP2024667B1 (de)
JP (1) JP5249930B2 (de)
KR (1) KR101433752B1 (de)
CN (1) CN101490442B (de)
AT (1) ATE474162T1 (de)
BR (2) BR122018073647B1 (de)
CA (1) CA2654651C (de)
DE (1) DE602007007760D1 (de)
GB (1) GB0611265D0 (de)
MX (1) MX2008015651A (de)
RU (1) RU2425268C2 (de)
WO (1) WO2007141564A2 (de)
ZA (1) ZA200900026B (de)

Cited By (2)

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Publication number Priority date Publication date Assignee Title
US20120202643A1 (en) * 2010-12-15 2012-08-09 Long Charles F Variator multiplex valve scheme for a torroidal traction drive transmision
US11077683B2 (en) * 2019-02-28 2021-08-03 Brother Kogyo Kabushiki Kaisha Image forming apparatus and storage medium

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0703353D0 (en) * 2007-02-21 2007-03-28 Torotrak Dev Ltd Continuously variable transmission
US8613681B2 (en) * 2009-11-19 2013-12-24 GM Global Technology Operations LLC Transmission hydraulic control system having clutch compensator feed override

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US1861303A (en) * 1930-10-25 1932-05-31 Yarman Grover R De Friction drive for feed grinder drags
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US3561281A (en) * 1968-09-06 1971-02-09 Thomas Wilfert Safety control lever
GB1367525A (en) 1971-12-08 1974-09-18 Gkn Transmissions Ltd Variable ratio traction drive
GB1494128A (en) 1974-04-06 1977-12-07 Papadimitriou Ioannis Transmission system
US4434676A (en) 1982-03-22 1984-03-06 Excelermatic Inc. Traction roller transmission with mechanical transmission ratio control
US4554841A (en) * 1983-11-04 1985-11-26 Nippon Seiko Kabushiki Kaisha Speed control device of a toric type infinitely variable transmission
GB2177765A (en) 1985-06-15 1987-01-28 Robert Bishop Improvements relating to automatic transmission systems
US4752278A (en) 1986-01-14 1988-06-21 Fiat Auto S.P.A. Manually-operated control device for a motor vehicle gearbox comprising a variator
US5230669A (en) 1989-01-30 1993-07-27 Tervola Pentti J Stepless transmission with disconnectable neutral seeking mechanism
GB2312257A (en) 1996-04-19 1997-10-22 Torotrak Dev Ltd Toroidal race variator control system varies end loading according to net pres sure

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Publication number Priority date Publication date Assignee Title
GB220331A (en) 1923-08-10 1925-05-07 Richard Erban Improvements in and relating to variable-speed gearing
US1861303A (en) * 1930-10-25 1932-05-31 Yarman Grover R De Friction drive for feed grinder drags
GB415076A (en) 1932-03-04 1934-08-16 Oloudsley Engineering Company Improvements in or relating to variable speed power transmission mechanism
US3561281A (en) * 1968-09-06 1971-02-09 Thomas Wilfert Safety control lever
GB1367525A (en) 1971-12-08 1974-09-18 Gkn Transmissions Ltd Variable ratio traction drive
GB1494128A (en) 1974-04-06 1977-12-07 Papadimitriou Ioannis Transmission system
US4434676A (en) 1982-03-22 1984-03-06 Excelermatic Inc. Traction roller transmission with mechanical transmission ratio control
US4554841A (en) * 1983-11-04 1985-11-26 Nippon Seiko Kabushiki Kaisha Speed control device of a toric type infinitely variable transmission
GB2177765A (en) 1985-06-15 1987-01-28 Robert Bishop Improvements relating to automatic transmission systems
US4752278A (en) 1986-01-14 1988-06-21 Fiat Auto S.P.A. Manually-operated control device for a motor vehicle gearbox comprising a variator
US5230669A (en) 1989-01-30 1993-07-27 Tervola Pentti J Stepless transmission with disconnectable neutral seeking mechanism
GB2312257A (en) 1996-04-19 1997-10-22 Torotrak Dev Ltd Toroidal race variator control system varies end loading according to net pres sure

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US20120202643A1 (en) * 2010-12-15 2012-08-09 Long Charles F Variator multiplex valve scheme for a torroidal traction drive transmision
US8721494B2 (en) * 2010-12-15 2014-05-13 Allison Transmission, Inc. Variator multiplex valve scheme for a torroidal traction drive transmision
US20140249725A1 (en) * 2010-12-15 2014-09-04 Allison Transmission, Inc. Variator Multiplex Valve Scheme for a Torroidal Traction Drive Transmission
US9562594B2 (en) * 2010-12-15 2017-02-07 Allison Transmission, Inc. Variator multiplex valve scheme for a torroidal traction drive transmission
US11077683B2 (en) * 2019-02-28 2021-08-03 Brother Kogyo Kabushiki Kaisha Image forming apparatus and storage medium

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EP2024667A2 (de) 2009-02-18
US20090318259A1 (en) 2009-12-24
RU2008152318A (ru) 2010-07-20
RU2425268C2 (ru) 2011-07-27
JP5249930B2 (ja) 2013-07-31
MX2008015651A (es) 2009-01-09
CA2654651C (en) 2015-02-17
ATE474162T1 (de) 2010-07-15
WO2007141564A2 (en) 2007-12-13
CN101490442A (zh) 2009-07-22
DE602007007760D1 (de) 2010-08-26
BRPI0712137B1 (pt) 2019-02-05
CN101490442B (zh) 2014-12-10
GB0611265D0 (en) 2006-07-19
BR122018073647B1 (pt) 2019-04-16
EP2024667B1 (de) 2010-07-14
BRPI0712137A2 (pt) 2012-01-10
WO2007141564A3 (en) 2008-03-06
KR20090018681A (ko) 2009-02-20
JP2009540231A (ja) 2009-11-19
CA2654651A1 (en) 2007-12-13
ZA200900026B (en) 2010-03-31
KR101433752B1 (ko) 2014-08-25

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